Pay Currency

Overview

How it works and where it fits

Pay Currency identifies the asset that moves on-chain from the payer to the payment destination. In a white-label request, OxaPay requires this field because the merchant is managing the payment interface and needs a specific asset and address.

The pay currency differs from Base Fiat Currency and Display Currency. An invoice can be priced and shown in USD while the payer sends TRX or USDT. The payment record must preserve both the pricing unit and crypto transfer unit.

A pay currency can exist on more than one network. Selecting USDT, for example, is incomplete until the exact network and token contract or provider network identifier are known. The destination must be validated against that combination.

The expected crypto amount is normally calculated from a quote. Rate movement and Quote Expiration can change the amount needed for a new session. Once a payment is created, its quoted amount and expiry should remain auditable.

Matching logic should verify pay currency, network, address, and amount before updating the payment state. A transfer in a different asset cannot be accepted merely because its market value is similar unless the product explicitly supports mixed-payment handling.

When a payer changes the selected asset, the system should create or refresh the payment instructions rather than editing only the symbol on screen. The network, address, amount, QR code, rate, and expiry can all change. A previously generated destination should be invalidated or clearly separated so the customer cannot accidentally pay with the old selection.

If the asset is temporarily unavailable after selection, the system should invalidate the session and request a new choice. It should not substitute another currency automatically because the payer may have different wallet, fee, or risk preferences.

Related glossary concepts

One-Time Payment Address; Payment Address Checksum; Payment Address Normalization